Nicene and Post-Nicene Fathers, Ser. II, Vol. XI:
The Works of John Cassian.: Chapter III. He proves from the Epistle to the Romans the eternal Divinity of Christ.

Chapter III.

He proves from the Epistle to the Romans the eternal Divinity of Christ.

And so as it is clear from the above testimony that God sent His own Son, and that He who was ever the Son of God became the Son of man, let us see whether the same Apostle gives any other testimony of the same sort elsewhere, that the truth which is already clear enough in itself, may be rendered still more clear by the light of a twofold testimony. So then the same Apostle says: “God sent His own Son in the likeness of sinful flesh.” 2449 You see that the Apostle certainly did not use these words by chance or at random, as he repeated what he had already said once—for indeed there could not be found in him chance or want of consideration as the fulness of Divine counsel and speech had taken up its abode in him. What then does he say? “God sent His own Son in the likeness of sinful flesh.” He says the same thing again and repeats it, saying, “God sent His own Son.” Oh renowned and excellent teacher! for knowing that in this is contained the whole mystery 2450 of the Catholic faith, in order that it might be believed that the Lord was born in the flesh and that the Son of God was sent into this world, again and again he makes the same proclamation saying, “God sent His own Son.” Nor need we wonder that he who was specially sent to preach the coming of God, made this announcement, since even before the law, the giver of the law himself proclaimed it, saying: “I beseech Thee, O Lord, provide another whom Thou mayest send,” or as it stands still more clearly in the Hebrew text: “I beseech Thee, O Lord, send whom Thou wilt send.” 2451 It is clear that the holy prophet, p. 575 feeling in himself a yearning for the whole human race, prayed as it were with the voices of all mankind to God the Father that He would send as speedily as possible Him who was to be sent by the Father for the redemption and salvation of all men, when he said, “I beseech Thee, O Lord, send whom Thou wilt send.” “God,” he therefore says, “sent His own Son in the likeness of sinful flesh.” Full well, when he says that He was sent in the flesh, does he exclude for Him sin of the flesh: for he says “God sent His own Son in the likeness of the flesh of sin,” in order that we may know that though the flesh was truly taken, yet there was no true sin, and that, as far as the body is concerned, we should understand that there was reality; as far as sin is concerned, only the likeness of sin. For though all flesh is sinful, yet He had flesh without sin, and had in Himself the likeness of sinful flesh, while He was in the flesh but He was free from what was truly sin, because He was without sin: and therefore he says: “God sent His own Son in the likeness of sinful flesh.”

Footnotes

Rom. viii. 3.

Sacramentum.

Exod. iv. 13. Where the LXX. has Δέομαι, κύριε, προχείρισαι δυνάμενον ἄλλον ὃν ἀποστελεῖς, which was followed by the old Latin. Jerome however rendered the passage correctly from the Hebrew: “obsecro, Domine, mitte quem misurus es.” Cf. the note on the Institutes, XII. xxxi.